Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$106.75	4.516%	$111.5708	$111.57	$111.55	$111.60
Purchase #2	$20.35	4.830%	$21.3329	$21.33	$21.35	$21.30
Purchase #3	$54.62	11.164%	$60.7178	$60.72	$60.70	$60.70
Purchase #4	$155.63	11.709%	$173.8527	$173.85	$173.85	$173.90
Purchase #5	$86.51	13.845%	$98.4873	$98.49	$98.50	$98.50
Purchase #6	$235.30	6.149%	$249.7686	$249.77	$249.75	$249.80
Purchase #7	$218.82	5.818%	$231.5509	$231.55	$231.55	$231.60
7 purchase totals =	$877.98		$947.2810	$947.28	$947.25	$947.40